People often have trouble performing 2 relatively simple tasks concurrently. The causes of this interference and its implications for the nature of attentional limitations have been controversial for 40 years, but recent experimental findings are beginning to provide some answers. Studies of the psychological refractory period effect indicate a stubborn bottleneck encompassing the process of choosing actions and probably memory retrieval generally, together with certain other cognitive operations. Other limitations associated with task preparation, sensory-perceptual processes, and timing can generate additional and distinct forms of interference. These conclusions challenge widely accepted ideas about attentional resources and probe reaction time methodologies. They also suggest new ways of thinking about continuous dual-task performance, effects of extraneous stimulation (e.g., stop signals), and automaticity. Implications for higher mental processes are discussed.

https://psycnet.apa.org/journals/bul/116/2/220.pdf

Dual-task interference in simple tasks: Data and theory.

In this provocative book, Barwise and Perry tackle the slippery subject of \"meaning, \" a subject that has long vexed linguists, language philosophers, and logicians.

/pdf/situations-and-attitudes-57f065zg2d.pdf

Situations and Attitudes.

According to Fitts' law, human movement can be modeled by analogy to the transmission of information. Fitts' popular model has been widely adopted in numerous research areas, including kinematics, human factors, and (recently) human-computer interaction (HCI). The present study provides a historical and theoretical context for the model, including an analysis of problems that have emerged through the systematic deviation of observations from predictions. Refinements to the model are described, including a formulation for the index of task difficulty that is claimed to be more theoretically sound than Fitts' original formulation. The model's utility in predicting the time to position a cursor and select a target is explored through a review of six Fitts' law studies employing devices such as the mouse, trackball, joystick, touchpad, helmet-mounted sight, and eye tracker. An analysis of the performance measures reveals tremendous inconsistencies, making across-study comparisons difficult. Sources of experimental variation are identified to reconcile these differences.

Fitts' law as a research and design tool in human-computer interaction

A stochastic optimized-submovement model is proposed for Pitts' law, the classic logarithmic tradeoff between the duration and spatial precision of rapid aimed movements. According to the model, an aimed movement toward a specified target region involves a primary submovement and an optional secondary corrective submovement. The submovements are assumed to be programmed such that they minimize average total movement time while maintaining a high frequency of target hits. The programming process achieves this minimization by optimally adjusting the average magnitudes and durations of noisy neuromotor force pulses used to generate the submovements. Numerous results from the literature on human motor performance may be explained in these terms. Two new experiments on rapid wrist rotations yield additional support for the stochastic optimizedsubmovement model. Experiment 1 revealed that the mean durations of primary submovements and of secondary submovements, not just average total movement times, conform to a square-root approximation of Pitts' law derived from the model. Also, the spatial endpoints of primary submovements have standard deviations that increase linearly with average primary-submovement velocity, and the average primary-submovement velocity influences the relative frequencies of secondary submovements, as predicted by the model. During Experiment 2, these results were replicated and extended under conditions in which subjects made movements without concurrent visual feedback. This replication suggests that submovement optimization may be a pervasive property of movement production. The present conceptual framework provides insights into principles of motor performance, and it links the study of physical action to research on sensation, perception, and cognition, where psychologists have been concerned for some time about the degree to which mental processes incorporate rational and normative rules. An enduring issue in the study of the human mind concerns of mathematical probability theory and statistical decision thethe rationality and optimality of the mental processes that guide ory (e.g., see Edwards, 1961; Edwards, Lindman, & Savage,

/pdf/optimality-in-human-motor-performance-ideal-control-of-rapid-2whgus6jwu.pdf

Optimality in human motor performance: Ideal control of rapid aimed movements.

The authors' goal is to apply robotics and automation technology to assist, enhance, quantify, and document neurorehabilitation. This paper reviews a clinical trial involving 20 stroke patients with a prototype robot-aided rehabilitation facility developed at the Massachusetts Institute of Technology, Cambridge, (MIT) and tested at Burke Rehabilitation Hospital, White Plains, NY. It also presents the authors' approach to analyze kinematic data collected in the robot-aided assessment procedure. In particular, they present evidence (1) that robot-aided therapy does not have adverse effects, (2) that patients tolerate the procedure, and (3) that peripheral manipulation of the impaired limb may influence brain recovery. These results are based on standard clinical assessment procedures. The authors also present one approach using kinematic data in a robot-aided assessment procedure.

/pdf/robot-aided-neurorehabilitation-2u069301n4.pdf

Robot-aided neurorehabilitation

Contents: Preface. Perception/Action: A Systems Approach. Closing the Loop. Information Theory and Fitts' Law. The Step Response: First-Order Lag. Linear Systems: Block Diagrams and Laplace Transforms. The Step Response: Second-Order System. Nonproportional Control. Interactions Between Information and Dynamic Constraints. Order of Control. Tracking. There Must Be 50 Ways to See a Sine Wave. A Qualitative Look at Fourier Analysis. The Frequency Domain: Bode Analysis. The Frequency Domain: Describing the Human Operator. Additional Adaptive Aspects of the Crossover Model. Driving Around in Circles. Continuous Tracking: Optimal Control. Estimating and Predicting the State of a Dynamic System With Lag-Like Calculations. Varieties of Variability. Lifting a Glass of Juice. Sine Wave Tracking Is Predictably Attractive. Going With the Flow: An Optical Basis for the Control of Locomotion. Fuzzy Approaches to Vehicular Control. Learning to Control Difficult Systems: Neural Nets. Some Parallels Between Decision Making and Manual Control. Designing Experiments With Control Theory in Mind. Adaptation and Design. Appendix: Interactive Demonstrations.

Control Theory for Humans: Quantitative Approaches To Modeling Performance

Subjects performed two-dimensional discrete movements either with a helmet-mounted sight or with a joystick. Fitts’ Law was found to be a good predictor of the speed-accuracy tradeoff for both systems. The joystick produced faster movement times than the helmet-mounted sight. For both systems, horizontal and vertical movements were slightly faster than diagonal movements. Two dimensional generalizations of Fitts’ Law were discussed in terms of multidimensional scaling. The obtained pattern of movement times was found to be intermediate to the predictions of Euclidean and City-block models of the movement space. Muscle coordination strategies were considered, and a strictly serial coordination model was rejected. A strictly parallel model was also rejected for the helmet-mounted sight, but not for the joystick.

Fitts' Law in two dimensions with hand and head movements.

Fitts' law and the microstructure of rapid discrete movements.

Subjects used either a position or a velocity control system to capture stationary and moving targets. Fitts' Index of Difficulty was found to be a good predictor of capture time for the rate syste...

A test of Fitts' law with moving targets.

Musically trained subjects tapped three beats with their right hand versus two beats with their left hand in synchrony with two corresponding tones For independent groups of subjects, the pitch difference of the two tones was either small to encourage an integrated perceptual organization or large to encourage a streamed perceptual organization Integrated versus parallel motor organization was tested by examining the pattern of covariances among intertap intervals All subjects exhibited integrated motor organization An integrated multiplicative hierarchical model of motor organization was superior to a serial chained model and to an independent hierarchical model in describing the pattern of covariances The subjects who heard tones that encouraged an integrated percept performed with less variability than the subjects who heard tones that encouraged a streamed percept This superior performance with an integrated motor organization and an integrated rather than a streamed perceptual organization is interpreted as evidence for temporal perceptual-motor compatibility

Richard J. Jagacinski

Papers

Control Theory for Humans: Quantitative Approaches To Modeling Performance

Fitts' Law in two dimensions with hand and head movements.

Fitts' law and the microstructure of rapid discrete movements.

A test of Fitts' law with moving targets.

Tests of parallel versus integrated structure in polyrhythmic tapping.